1. Field of the Invention
The present invention relates to an index apparatus for indexing a rotary table to a desired angular position.
2. Description of the Prior Art
When a gear coupling such as Curvic Coupling is used to index a rotary table of a machine tool, the number of teeth of the gear coupling is determined depending upon a minimum index angle of the rotary table. When the minimum index angle of the rotary table is more than 5 degrees, the number of teeth of the gear coupling is relatively small and the whole depth of the tooth is relatively large. Accordingly, even if a slight misalignment is produced between the complementarily engageable teeth, these teeth are forcibly engaged with each other. However, when the minimum index angle of the rotary table is small, for example, one degree, the number of teeth of the gear coupling becomes relatively large and the whole depth of the tooth becomes considerably smaller. Accordingly, if the rotary table is not accurately indexed, the engagement between the complementarily engageable teeth is not smoothly performed.